A mobile terminal such as a cell phone may, in addition to communication via a cellular mobile communication network, support near field communication (NFC) which for example allows using the mobile terminal as a train ticket, electronic wallet etc. It may be desirable or necessary that such a functionality is supported even if the main battery of the mobile terminal is exhausted. This can be done by drawing the required power from a NFC reader on which the mobile terminal is placed. It is desirable that the power supply by means of the energy received via NFC is implemented efficiently and at low cost.